The pair recounted the horror in Svalbard on August 5, 2011, during the inquest into the death of Eton pupil Horatio at Salisbury yesterday.

Mr Reid said he leapt out of his tent with his rifle as soon as he was awaked by voices from Horatio’s tent screaming “bear”.

According to witnesses, Horatio was confronted by the bear in the porch of his tent, where the animal began to maul his head as he tried to stand up.

When Mr Reid saw the bear attacking Horatio, he cocked the rifle and aimed at the bear’s chest, but the bullet simply dropped on to the ground.

“I cocked the rifle again and took another attempt at an aimed shot at the bear,” he said.

The bullet again just fell to the ground.

“I didn’t realise why this failure was happening. I carried on until the magazine was empty.

“The bear then came and attacked me. I remember the bear biting my head and I thought, the weakest part of this bear is his eyes, so I tried to take out his eyes with my fingers. But I was unsuccessful.”

He still has scars from the injuries he sustained in the incident which included a broken jaw, fractured skull and damage to his own eye sockets.

Eventually, Mr Ruck managed to distract the bear by hitting it with a rock, and Mr Reid was able to crawl away.

Shot down ... authorities remove the carcass of the polar bear at the Von Postbreen glacier in Tempelfjorden on August 5, 2011. Picture: AFP/Sysselmannen/Arild LyssandSource:AFP

The bear then turned on Mr Ruck and others in the camp. Mr Ruck recalled: “I charged towards the bear and shouted at it and picked up rocks and threw them at its face.

“The bear then attacked me. It knocked me to the floor and I remember its paws on my shoulders and seeing its face. It swiped my face with its claws and it had my head in its mouth at some point. The bear then left me for some reason. I had very few clear thoughts after that.” Although dazed and bloodied, Mr Reid still managed to shout to other team members to ask where his rifle was.

“Someone said it’s in your tent,” he said.

“I returned through the back door of the tent and found the rifle there. I exited through the front of the tent and tried to fire again one of the rounds that had been fired to the ground. I cocked the rifle and then fired at the bear as it was attacking someone else.”

Matthew Burke, 23, was one of the youngsters on the trip and was in a tent just a few metres from Horatio’s.

He said: “I saw Horatio in the porch of his tent.

“The bear was also in the porch. It used its paws and slammed down on Horatio.”

Mr Burke said he began jogging around the camp, keeping the teenagers in the other tents calm. He recalled seeing “bits and bobs” of the chaos, including Mr Ruck throwing stones.

Deadly scene ... trekkers stand among their tents in a camp after the polar bear attack at the Von Postbreen glacier in Tempelfjorden on August 5, 2011. Picture: AFP/Sysselmannen/Arild LyssandSource:AFP

Mr Burke said: “The bear was still on Spike at this time, then it moved away to attack Andy. After Andy was on the ground, the bear walked back to the tent with Horatio in it.”

He added he could see the bear “biting and clawing” at Horatio as he lay on top of his mangled tent.

After Mr Reid shot the bear, Mr Burke rushed over to Horatio.

He said: “He was dead. He wasn’t moving and I could kind of just tell.”

Paying tribute to Horatio, Mr Reid said: “He was a fantastic member of our team. He was a fine young gentleman with some amazing potential.”

The expedition, run by British Schools Exploring Society, cost £4000 but it has emerged that the team were forced to mend a safety trip-wire with paperclips because pieces of kit were missing.

Mr Reid said he “wished” he could have prevented the attack or stopped it sooner.

He added the group having more pen flares and receiving more rifle training would have been helpful.

Lizanne Gumbel, for the Chapples, said Mr Reid had been forced to “rely on the ingenuity of people who had not been trained”.

The inquest also heard that the rifle — a Mauser 98K — may not have fired because its safety catch was on.

Students Patrick Flinders, 16, from Jersey and Scott Bennell-Smith, 16, from Cornwall were also injured in the tragedy. The hearing continues.